The invention pertains to a therapy system comprising:
a therapy module to direct a therapeutic action to a target along successive trajectories in a target region that includes the target
a thermometry module to measure temperature a measurement field and in particular to compute a thermal dose,
a control module to control the therapy module to apply the therapeutic action along the respective trajectories on the basis of the measured temperature and/or thermal dose, wherein the successive trajectories are located in the target zone.
Such a therapy system is known from the international application WO2009/090579-A1 (PH009795).
Mild hyperthermia (HT) is a therapeutic technique in which tissue is heated to temperatures (e.g., 38-45° C.) above body temperature, but below ablative temperatures. These hyperthermia treatments may result in physiological (e.g., perfusion) and cellular (e.g., gene expression) changes that improve the therapeutic effectiveness when used in conjunction with chemotherapy or radiation therapy. HT induces a multitude of changes, which provide clinical benefits that make it synergistic with many chemotherapeutic agents and radiation therapy. In addition to physiological and cellular changes, hyperthermia may be used with temperature responsive or non-responsive drug delivery systems to reduce toxicity and improve overall efficacy. One solution for reducing toxicity involves targeting the tumor with temperature sensitive liposomal drug delivery. In experimental work, liposomes have exhibited near complete drug release within 10-20 seconds at mild hyperthermic temperatures (40-42° C.).
There are a number of currently available devices that can heat target tissue to the hyperthermic range. One example is radiofrequency (RF) applicators, which use tuned antennas to transmit RF energy into the body. However, RF applicators are best used to heat deep-seated tumors, due the long wavelengths of RF. Microwave applicators are also used, but are typically used only for superficial tumors due to their small wavelength. Both types can be used in different configurations, with the most common being phased arrays, waveguides, and spiral antennas. A novel, efficient way of performing local hyperthermia is by magnetic resonance guided high intensity focused ultrasound (MR-HIFU), in which focused ultrasound is used for achieving hyperthermia and MR is utilized to monitor the treatment.
MRI provides in vivo temperature maps during HIFU sonication. Feedback can then be realized by real-time evaluation of temperature elevations detected in the tissue, and adapting the power, duration or trajectory of the sonication based on this knowledge. Volumetric feedback has been previously used to thermally ablate tissue, i.e. achieve complete thermal necrosis in the target region (M. Kohler et al., Med. Phys. 36 (8), 3521, August 2009; J. Enholm et al., IEEE Trans. Biomed. Eng., 57 (1), January 2010). The international application WO 2009/090579-A1 mentions binary feedback for MR-HIFU ablation.